The installation quality of the guide rail of a lift, especially the error on perpendicularity, is an important factor affecting the proper operation of the lift. Detection of lift guide rail perpendicularity is a key step to ensure the installation quality of the lift. According to stipulations of GBJ310-88 Detection and Evaluation Standards for Engineering Quality of Lift Installation, the error allowance requirement for lift guide rail perpendicularity is 0.7 mm of per 5 m, using the “plumb line and dipstick metering” method. According to Lift Supervision and Detection Regulations issued by General Administration of Quality Supervision, Inspection and Quarantine of the People's Republic of China, 2002-1-9, the maximum error allowance per 5 m of working surface of each guide rail is as follows: 1.2 mm for car guide rails and T counterweight guide rails with safety gears; 2 mm for T counterweight guide rails without safety gears, using laser vertical collimator or magnetic plumb of 5 m in length, measuring along the side and top working surfaces of the guide rail, and detecting sectionally and continuously per 5 m along the vertical line and no less than three sections for each side. The “plumb line and dipstick metering” method has been used to detect guide rail perpendicularity for several decades. Its advantages are using simple measuring and metering tools and obtaining results directly from visual measurements but its shortcomings are inconsistent measuring accuracy among different operators with varying operating skill and visual reading errors, the difficulty for achieving automatic data collection, and low work efficiency.
In recent years, the method with laser vertical collimator is introduced for detecting lift guide rail perpendicularity. For example, the method with JZC-A laser vertical collimator of automatic alignment to detect lift guide rail perpendicularity has been applied for patent by LaTe Laser Technology Development Limited Company of Dalian Development Zone and has been used widely. The method has improved the measuring accuracy and work efficiency over the traditional method of “plumb line and dipstick metering.” However, while the pull wire is replaced by the laser beam in the newer method, both methods are basically identical in measuring theory and process. For the newer method, each detection position is still manually measured seriatim and data are still read and collected manually.